GSCI 1050 Lecture Notes - Lecture 25: Cubic Mile, Lake Nyos, Flux Melting
15 May 2017
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Document Summary
Journal 4 due tuesday by end of day. What affects explosivity: composition felsic magmas are more viscous/resistant to flow, temperature, volatility, note - low viscosity tends to mean gentler lava flaws. Supervolcano ash fall constitutes the most serious threat: map of yellowstone showing ash fall covering half of the us. Ashfall beds nebraska state park found fossils from variety of mammals in ash. Humans are drawn to volcanoes for soil, water, land and scenic resources. Historic eruptions range in power and effects over many orders of magnitude: mt. St. helens at top (. 24 cubic mile of ejected material) at top: toba (indonesia) (670 cubic miles) at bottom. Yellowstone: continental hot spot - cuts a continental plate, yellowstone - eruption ~640ka created a 100km caldera, a thousand times more powerful than mt. St. helens: deposited vast ignimbrite deposits in 3 gigantic eruptions, magma beneath the caldera continues to fuel geysers.
